Surveillance and other monitoring systems are typically dependent on the limitations of the applicable imaging system. The effective spatial and temporal resolution of current imaging systems is limited not only by the sensor pixel count, but also by onboard size, weight and power (SWAP) constraints and by communication bandwidth limitations.
Current imaging systems perform Nyquist sampling of optical images using sensor arrays in which each detector element records a single pixel in the image, which is digitized and stored in an array of pixel values (which can then be compressed). Conventional sampling is not adaptive to the task to be performed and is inefficient in hardware and computational resource utilization because it stores information that is not necessarily needed for a particular task. In addition, image resolution is limited by the physical number of detector elements, resulting in ever larger sensor arrays and SWAP/bandwidth requirements as mission requirements increase. Compressive Measurement or sensing (CM) is a potentially viable alternative to Nyquist sampling with a sound theoretical basis. It is based on the fact that images have sparse representations for certain sets of basis functions or dictionaries. CM has been used to reconstruct images using far fewer measurements than predicted by the Nyquist sampling criterion by preprocessing with random measurement matrices and using sparsity-enforcing optimization methods to reconstruct the image. Existing CM imaging systems, however, do not take advantage of prior knowledge about the data or the task to be performed with the imagery or real-time adaptation to the data, which limits the amount of SWAP and bandwidth reduction that can be achieved.
Thus, a continuing need exists for an image sensing system that incorporates task-aware sampling to greatly reduce the number of physical measurements needed to achieve a given level of task performance, thereby greatly increasing the utility of the sensing system while reducing SWAP and communication bandwidth requirements